A post marketing survey of the safety of venom immunotherapy was carried out. One thousand four hundred and ten insect sting alergic patients who were sensitive to FDA licensed hymenoptera venom by skin test were immunized. Twelve percent of patients immunized experienced adverse reactions, similar to the European experience with venom products. Most patients (92%) reached maintenance, most often 8 weeks into treatment, consistent with the dose regimen in the approved insert. Most adverse reactions occurred during buildup (1-50 %g) and at maintenance. No history of venom reactivity or skin sensitivity to venom predicted which patient was at risk of an allergic adverse reaction during venom therapy. These data demonstrate the relative safety of FDA licensed hymenoptera venom extracts when used according to package insert.